PSU got negative output!! help

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  • jdimpas
    Member
    • May 2008
    • 39

    #1

    PSU got negative output!! help

    hello guys, my powersupply is working however it has a negative output. Once i power on my computer the fan of the processor works but the entire system won't work. When I checked the output of my powersupply it has negative outputs. How does it happen like this?. Any brilliant ideas how to get through with this problem. Thanks so much! Godspeed..
  • jdimpas
    Member
    • May 2008
    • 39

    #2
    Re: PSU got negative output!! help

    Additional info:

    *Outputs in my PSU*

    Red = -5 DC Volts
    Yellow = -11.70 DC Volts
    Orange = -3.38 DC Volts
    Gray = -0.13 DC Volt
    Violet = -5.10 DC Volts
    Blue = +10.98 DC Volts
    White = +4.54 DC Volts

    Seems like inverted... help!

    Comment

    • Harvey
      Badcaps Veteran
      • Apr 2007
      • 264

      #3
      Re: PSU got negative output!! help

      You've got your leads plugged into your meter the wrong way around?

      Comment

      • jdimpas
        Member
        • May 2008
        • 39

        #4
        Re: PSU got negative output!! help

        Originally posted by Harvey
        You've got your leads plugged into your meter the wrong way around?
        Nope! the leads was connected correctly, in fact i tested other new power supply it has positive outputs. Black probes in the voltmeter was connected to ground of the powersupply(black cable).

        Comment

        • kc8adu
          Super Moderator
          • Nov 2003
          • 8832
          • U.S.A!

          #5
          Re: PSU got negative output!! help

          something up with the color codes?
          i dont know of any failure mode that can cause this.
          post a pic of this unit.
          brand,model,and open covers.

          Comment

          • Wizard
            Badcaps Legend
            • Mar 2008
            • 2296

            #6
            Re: PSU got negative output!! help

            I have seen this before. Like brown, blue, etc instead of standard black, red yellow, orange etc.

            Cheers, Wizard

            Comment

            • Wizard
              Badcaps Legend
              • Mar 2008
              • 2296

              #7
              Re: PSU got negative output!! help

              I have seen this before. Like brown, blue, etc instead of standard black, red yellow, orange etc.

              And what is this power supply from and picture will help.

              Cheers, Wizard

              Comment

              • jdimpas
                Member
                • May 2008
                • 39

                #8
                Re: PSU got negative output!! help

                Comment

                • jdimpas
                  Member
                  • May 2008
                  • 39

                  #9
                  Re: PSU got negative output!! help

                  All are properly connected from voltmeter to its test probes. Output seems to be inverted and i got 2 powersupply with same problem.

                  Comment

                  • linuxguru
                    Badcaps Legend
                    • Apr 2005
                    • 1564

                    #10
                    Re: PSU got negative output!! help

                    Check the DMM against an AA cell - it's probably wired wrongly internally.

                    Comment

                    • jdimpas
                      Member
                      • May 2008
                      • 39

                      #11
                      Re: PSU got negative output!! help

                      actually, what really happen was one of computer in the office suddenly shut off and when i turn it on the computer won't work. I checked this powersupply and i was amazed it got negative outputs, so i decided to replaced new powersupply to this computer and it was working fine. so basically, the problem was the powersupply with negative outputs.
                      Last edited by jdimpas; 06-17-2008, 02:27 AM.

                      Comment

                      • kc8adu
                        Super Moderator
                        • Nov 2003
                        • 8832
                        • U.S.A!

                        #12
                        Re: PSU got negative output!! help

                        looks like a harbor fright meter.bet it is backwards.
                        the psu in the pic is a gutless wonder.
                        experiment with it and toss it.not worth repairing and possibly not even safe to use.

                        Comment

                        • jdimpas
                          Member
                          • May 2008
                          • 39

                          #13
                          Re: PSU got negative output!! help

                          Originally posted by kc8adu
                          looks like a harbor fright meter.bet it is backwards.
                          the psu in the pic is a gutless wonder.
                          experiment with it and toss it.not worth repairing and possibly not even safe to use.
                          I just wondering how does the VDC output goes inverted (negative)? im not quite familiar with this problem. Do you have any technical explanation with this?

                          Comment

                          • kc8adu
                            Super Moderator
                            • Nov 2003
                            • 8832
                            • U.S.A!

                            #14
                            Re: PSU got negative output!! help

                            unless someone swapped the diodes in the psu they dont.
                            the meter is wrong.or someone played a prank on you.
                            they would also have to reverse the caps or they would explode.

                            Comment

                            • jdimpas
                              Member
                              • May 2008
                              • 39

                              #15
                              Re: PSU got negative output!! help

                              i need someone knows the problem..

                              Comment

                              • linuxguru
                                Badcaps Legend
                                • Apr 2005
                                • 1564

                                #16
                                Re: PSU got negative output!! help

                                Why doesn't the dumbfuck just check the DMM against a source with known polarity?

                                Comment

                                • kc8adu
                                  Super Moderator
                                  • Nov 2003
                                  • 8832
                                  • U.S.A!

                                  #17
                                  Re: PSU got negative output!! help

                                  i smell a troll.

                                  Comment

                                  • Krankshaft
                                    Badcaps Legend
                                    • Jan 2007
                                    • 2328
                                    • USA

                                    #18
                                    Re: PSU got negative output!! help

                                    I would chuck that supply as KC said thats one of those "lets see how many components we can remove until the PSU doesn't work anymore" supplies.

                                    If it was a well designed supply then it would be worth it.

                                    EMI filter don't need it safety caps don't need em.

                                    A jumper wire works just as well NOT!!!

                                    I really wonder how anyone with a conscience could design and sell a supply like this.

                                    I can see the original designer silkscreened the safety components on the board but the beancounters started chopping parts out during the building process.

                                    Look at those tiny descrete diodes for the line rectifier pathetic I'd love to draw the full rated 250 watts the thing would probably go up like a roman candle .

                                    It doesn't look like it even uses an opto isolator they used a transformer for feedback isolation.
                                    Last edited by Krankshaft; 06-17-2008, 04:45 PM.
                                    Elements of the past and the future combining to make something not quite as good as either.

                                    Comment

                                    • PCBONEZ
                                      Grumpy Old Fart
                                      • Aug 2005
                                      • 10661
                                      • USA

                                      #19
                                      Re: PSU got negative output!! help

                                      You have the meter leads in the wrong holes.
                                      The bottom hole says "common" - that's ground - that where the black wire goes.

                                      .
                                      Mann-Made Global Warming.
                                      - We should be more concerned about the Intellectual Climate.

                                      -
                                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                                      - Dr Seuss
                                      -
                                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                      -

                                      Comment

                                      • Brian C
                                        Senior Member
                                        • Dec 2006
                                        • 156

                                        #20
                                        Re: PSU got negative output!! help

                                        This guy must have used the wrong lead connections. Please refer to the attached picture. Common (black lead) should be at the bottom hole. That's why he reads negative voltages, as the current measurement lead has very low resistance to common.

                                        Attached Files
                                        Last edited by Brian C; 06-17-2008, 05:57 PM.

                                        Comment

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